A adaptação dos animais ao ambiente criatório é essencial para o êxito de qualquer empreendimento pecuário. No Brasil, há algumas décadas, foram importadas inúmeras raças, oriundas de clima temperado, das mais diversas espécies de animais de produção, cujas progênies eram avaliadas e selecionadas em consideração apenas dos aspectos produtivos. Nos últimos dez anos, verificou-se que tanto criadores, como a comunidade acadêmica, despertaram para a valorização de aspectos adaptativos, ao selecionarem animais a serem criados nos mais diversos biomas brasileiros. Observa-se, assim, a valorização das raças nativas de pequenos ruminantes e zebuínos para a exploração de carne e leite. No entanto, avaliar e selecionar animais pelas características adaptativas requer uma padronização de parâmetros e metodologias para a colheita de dados confiáveis. Ao se considerar que a homeostase representa a condição de equilíbrio em um sistema biológico e que animais adaptados ao ambiente exibem claros sinais de homeostasia, procurou-se, neste trabalho, abordar uma metodologia fundamentada numa matriz multifatorial para avaliar a adaptação, na qual são consideradas as reações termorreguladoras, como forma de manter a homeotermia, indicadas pelas temperaturas retal e de superfície, acionamento da termólise evaporativa, representadas pela frequência respiratória e taxa de sudação. Para avaliação da homeostase recomenda-se a associação de reações endócrinas, tais como níveis circulantes de hormônios da tireoide e cortisol, aos parâmetros bioquímicos dentro da faixa de normalidade. Todos esses fatores, em equilíbrio, permitem aos animais expressar satisfatoriamente as funções reprodutiva e produtiva.

RESUMO -Este trabalho foi conduzido com o objetivo de estudar o comportamento anual de características termorreguladoras de 200 vacas leiteiras. Durante dois anos consecutivos, foram registradas a freqüência respiratória (FR) e a temperatura retal (TR), bem como coletada uma amostra de sangue para dosagens de triiodotironina (T 3 ) e tiroxina (T 4 ).Foram também registradas a temperatura e a umidade do ar e calculados o índice de temperatura de globo e umidade (ITGU) e a carga térmica radiante (CTR), nos mesmos dias de coleta. Houve efeito significativo do ano para a maioria das variáveis estudadas, no entanto, os efeitos do mês de coleta e do rebanho foram significativos para todas. Todos os valores de TR estiveram dentro da amplitude de normalidade, indicando homeotermia. A FR foi alterada em todas as épocas do ano e rebanhos, confirmando a necessidade constante de termólise. No rebanho de maior TR e a FR, houve redução da secreção de T 3 e T 4 . Nas épocas de maiores ITGU e CTR, houve aumento da TR, seguido de maiores FR e menores concentrações plasmáticas de T 3 e T 4 .Palavras-chave: bovinos leiteiros, estresse térmico, termorregulação Annual thyroid hormone variation and thermo regulators traits of milk cows in hot environmentABSTRACT -This work was carried out with the objective to study the annual behavior of thermo regulators traits in dairy cows. Two hundred cows were used during two consecutive years and the respiratory rate (RR), rectal temperature (RT), as well as a blood sample was collected for triiodothyronin (T 3 ) and thyroxin (T 4 ) dosages, were recorded. Air temperature and humidity were also recorded and the black globe humidity index (BGHI) and radiant heat load (RHL) were calculated in the same days of data collection. There was no significative effect of the year for the majority of studied variables, however, the effects of month of collection and herd were significative for all variables. All values of RT were inside of the amplitude of normality, indicating homoeothermic condition. The RR was altered in every seasons of the year and herds, showing a constant necessity of thermolisys. In herds with higher RT and RR, there was a reduction T 3 and T 4 liberation. In seasons of higher BGHI and RHL, there was increase in the RT, followed for higher RR and lower T 3 and T 4 plasmatic concentrations.

RESUMO -Objetivou-se analisar a variação do pH, da amônia ruminal e do balanço de compostos nitrogenados e a síntese de proteína microbiana de 12 vacas da raça Holandesa distribuídas em três quadrados latinos 4 × 4, alimentadas com dietas contendo soja em diferentes formas: farelo de soja (dieta controle), soja crua, soja tostada e farelo de soja + 5% de ureia,

RESUMO -O objetivo neste trabalho foi estudar a variação anual da temperatura superficial e outras características do pelame de vacas holandesas em ambiente tropical, considerando separadamente as malhas negras e brancas. Foram medidas as características espessura da capa (mm), comprimento dos pelos (mm), número de pelos (pelos/cm 2 ) e temperatura da superfície do pelame em 191 vacas mestiças com alta proporção de sangue holandês (7/8 e 31/32, respectivamente), distribuídas em três rebanhos em ambiente semiárido. O pelame menos denso, com pelos mais curtos e assentados, que ocorreu predominantemente no mês de março, coincidiu com altos níveis de radiação solar. Esse tipo de pelame apresenta menor resistência ao fluxo de calor latente e sensível através da capa, favorecendo a termólise. A temperatura da superfície do pelame preto foi em média 4ºC maior que a do pelame branco ao longo do ano e essa variação acompanhou a da temperatura radiante média. Os modelos desenvolvidos para predizer a condutividade térmica efetiva do pelame devem considerar essas diferenças, pois, no caso de animais Holandeses malhados de preto e branco, manejados em ambiente tropical, o gradiente de temperatura no sentido horizontal não é negligível, assim como as características da capa também não o são.Palavras-chave: adaptação, ambiente tropical, bovinos leiteiros, capa externa Anual variation of morphologic traits and hair coat surface temperature of Holstein cows in semi-arid environmentABSTRACT -This work aimed to study the annual variation of temperature of the coat surface and other traits of coat in Holstein cows managed in a tropical environment by separately considering black coat and white coat. It was measured the coat thickness (mm) characteristic, hair length (mm), hair number (hair/cm 2 ) and coat surface temperature on 191 crossbred cows with 7/8 and 31/32 Holstein composition distributed in 3 herds in a semi-arid environment. Less dense coats with shorter, flattened hair occurred predominantly in March, a time coinciding to high levels of solar radiation. This type of coat shows low resistance to the flux of latent and sensitive heat through the skin, thus favoring heat loss. The black coat surface temperature was on average 4ºC higher than that of the white one during all the year and its variation followed that of the mean radiant temperature. The models developed to predict the effective thermal conductivity of the coat must take these differences into account because the thermal gradient parallel to the skin surface is not negligible for Holstein cows under the sun in a tropical environment, as well as the other traits.

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The effect of the natural weather conditions on respiratory rate, rectal temperature and hematologic parameters such as glucose, total cholesterol, triacylglycerol, total protein, albumin, globulin, red blood cells, microhematocrit, mean corpuscular volume, serum triiodothyronine (T 3 ) and thyroxine (T 4 ) levels was evaluated in red (RMN) and white (WMN) coat colored Morada Nova ewes, of different class of body condition score (CBCS), during the dry (from july to december) and wet (from january to june) seasons, which exhibited different (P<0.05) air temperature, relative humidity and radiant thermal load averages. Tukey's test was used and the difference considered was to P<0.05. Significant greater averages of respiratory rate were observed in the dry period compared to the rainy period (42.26±8.96 and 36.89±8.20 breaths min -1 , respectively), mainly in the RMN (45.54±8.23 breaths min -1 ) compared with the WMN (39.27±8.57 breaths min -1 ). No differences were observed in rectal temperature measurements between the dry and the wet periods (38.59±0.58 and 38.60±0.56 o C, respectively), but the WMN had higher values than the RMN (38.77±0.54 and 38.40±0.54 o C, respectively). The glucose and total cholesterol were higher in the wet season, with no variation due to breed variety and CBCS. The triacylglycerol did not change between breed varieties and seasons. The albumin was similar between varieties and in different seasons, being different in CBCS. Total protein and globulin serum were higher during the wet season, but total protein was higher and globulin was lower in better CBCS. T 3 and T 4 levels were higher in the rainy season (0.25±0.07 and 6.74±11.37 µg dL -1 , for T 3 and T 4 , respectively) than in the dry season (0.18±0.08 and 6.31±1.64 µg dL -1 , for T 3 and T 4 , respectively). The red blood cells showed no difference, but microhematocrit was higher in WMN and in the better CBCS and mean corpuscular volume was higher in the dry season. The concentration of T 3 was lower in the RMN than in the WMN (0.19±0.07 and 0.24±0.08 µg dL -1 , respectively), while T 4 did not differ between them (6.53±1.51 and 6.52±1.46 µg dL -1 , respectively). The Morada Nova sheep showed positive physiological responses to the heat stress, notably an increase of respiratory rate and a reduction of T 3 and T 4 levels. All another hematologic parameters analyzed were within the normal range for all sheep, indicating a good ability to cope with the climatic changes of the Brazilian semiarid region. Both varieties were heat tolerant, but the red variety required major adjustments to maintain homeothermy. Key words: Adaptation, blood metabolites, blood parameters, sheep, thermoregulatory responses, thyroid hormones ResumoNeste estudo foram avaliados os efeitos da época do ano nas características fisiológicas de frequência respiratória e temperatura retal e nos parâmetros hematológicos glicose, colesterol total, triglicerídeos, proteínas totais, albumina, globulina, contagem total de hemácias, hematócrito, volume corpu...

The aim of this study was to characterize the production systems and milk quality of eight milk production units (MPU) in the semiarid region of the state of Ceará, Brazil. Individual interviews were conducted through a questionnaire on the characteristics of the properties and production systems. Samples of milk and water were collected for a period of 12 months. Four MPUs were classified as semi-specialized and four as non-specialized. No differences were observed in milk composition between the two production systems, and both showed protein, fat, and solids-not-fat levels. Differences were observed for somatic cell count. The semi-specialized systems showed an average somatic cell and total bacterial count which is above the limit established by the 62nd Normative Instruction. All water samples showed presence of Escherichia coli. Somatic cell count was positively correlated (fat) and negatively (lactose). For total bacterial count, correlations were negative for fat, total solids, and somatic cell count. The microbiological quality of milk is not in accordance with the 62st and 7th Normative Instructions. The specialization of the production systems did not result in improved microbiological aspects of milk.